Generally speaking, liquefied natural gas (LNG) presents a viable fuel alternative to, for example, gasoline and diesel fuel. More specifically, LNG may be utilized as an alternative fuel to power certain vehicles. However, a primary concern in commercializing LNG includes accurately measuring the amount of LNG that is dispensed for use. Particularly, the National Institute of Standards and Technology of the United States Department of Commerce has developed guidelines for federal Weights and Measures certification, whereby dispensed LNG must be metered on a mass flow basis with a certain degree of accuracy. Such a mass flow may be calculated by measuring a volumetric flow rate of the LNG and applying a density factor of the LNG to that volumetric flow rate.
Typically, LNG dispensers may be employed to dispense LNG for commercial use. Such LNG dispensers may use mass flow measuring devices, such as a Corilois-type flow meter, or may include devices to determine the density of the LNG and the volumetric flow of the LNG. For example, the density may be determined by measuring the dielectric constant and the temperature of the LNG flowing through the dispenser. As the LNG flows through a dispensing chamber of the dispenser, a capacitance probe may measure the dielectric constant, and a temperature probe may measure the temperature. The measured dielectric constant and temperature may then by utilized to calculate the density of LNG flowing through the dispenser by known principles. A volumetric flow rate of the LNG may then be determined by, for example, a volumetric flow meter associated with the dispensing chamber. The acquired density and volumetric flow rate may be used to compute the mass flow rate of the dispensed LNG.
The existing configuration of LNG dispensers may have certain limitations. For example, LNG dispensers utilizing a Coriolis-type flow meter must be cooled to a suitable LNG temperature prior to dispensing, which requires metered flow of LNG to be diverted back to an LNG source. In addition, Coriolis-type flow meters are generally expensive. Furthermore, typical LNG dispensers house both the density-measuring device and the volumetric flow-measuring device within the same chamber, which results in and undesirably bulky LNG dispenser. The dispenser of the present disclosure is directed to improvements in the existing technology.